Electric ignition system



Patented Nov. 12, 1940 UNITED STATES PATENT OFFICE ELECTRIC IGNITION SYSTEM William H. Maycock, Coventry, England, assignor to General Electric Company, a. corporation of New York 6 Claims.

This invention relates to an electric ignition system for an internal combustion engine and more particularly to an electric ignition system for starting an internal combustion engine.

5 Heretofore the starting of an internal combustion engine which has a magneto to provide the electric ignition .has been accomplished through the use of an auxiliary hand-turned or motor-turned magneto or by a battery operated 10 trembler coil. The high voltage induced in the secondary windings of the starting ignition arrangement is fed through a trailing electrode on the main magneto distributor brush holder, and is then distributed to the appropriate distributor 15 electrode so as to provide-a spark at the spark plug for starting purposes.

An object of my invention is to provide an improved ignition arrangement for starting an internal combustion engine.

20 A further object of my invention is to impress a voltage of varying magnitude on the primary winding of a magneto to provide the necessary electric ignition for starting an internal combustion engine.

25 Further objects and advantages of my invention will become apparent from the following description referring to the accompanying drawing,

and the features of novelty which characterize,

my invention will be pointed out with particu- 30 larity in the claims annexed to and forming a part of this specification.

, In the drawing, Fig. 1 diagrammatically illustrates a mogneto ignition circuit provided with an embodiment of my improved starting arrange- 35 ment; Fig. 2 is a modification of the starting arrangement shown in Fig. 1; and Fig. 3 is a modification of the starting arrangement shown in Fig. 2.

Referring to the drawing, in Fig. 1 I have il- 40 lustrated diagrammatically a conventional magneto ignition system including a magneto |0 having a core member II with a primary winding [2 anda secondary winding l3 wound thereon. To provide the necessary cyclic secondary windings through the core member. The rotatable member, of course, is connected to the crankshaft of the internal combustion engine either directly or through suitable gears, and upon rotation thereof a current will be induced 5 in the primary winding 12. Upon the interruption of the primary winding circuit by the breaker I4 which is operated by the crank-shaft either directly or by means of suitable gears through the cam member I9, a voltage will be induced in the secondary winding I3 at the time the rotating brush of the distributor I6 is opposite a proper segment. Sufiicient voltage to operate the plug I I will only be obtained when a speed faster than starting or cranking speed is reached due to inherent characteristics of the magneto circuit. It is, of course, to be understood that any dynamoelectric machine of the magneto type may be used which is designed to produce the desired voltage in the secondary circuit for the particular engine with which it is to be used.

It is therefore apparent from the above description that a magneto cannot produce the'desired ignition until its rotatable member has begun to rotate at a speed faster than starting speed Since this rotation is caused by the engine through its crank-shaft it is obvious that some auxiliary arrangement must be used to produce the ignition during the starting of the engine.. I provide the desired ignition duringstarting by impressing a suitable voltage of varying magnitude on the primary winding of the magneto. In the circuit diagram shown in Fig. 1 this voltage which may be from a source of alternating current is connected across the terminals 20 and 2|. ,This voltage may be produced in any desired manner, and in Fig. 2 I have shown a simple and effective arrangement which includes a coil in circuitwith a unidirectional potential.

The energy source of this voltage includes a bat- I tery-22 across which is connected a trembler device which includes an inductance or coil 23 and an interrupter having contacts 24 and 25. In order that there may be provided a pulsating voltage across the inductance or trembler coil, the coil is connected to the battery through the contacts 24 and 25. The contact 25 is carried by an armature 26 which is adapted to cooperate with the core member 21 of the trembler coil and the contact 24 is held stationary. Thus when the switch 28 is closed current will flow through the contacts 24 and 25 to the trembler coil. .This flow of current will set up a magnetic field which attracts the armature and opens the contacts. A suitable capacitor 29 may be placed across these contacts so as to minimize arcing. Whenthe contacts open the direct current stops flowing in the trembler coil and the magnetic field begins to subside. Since the armature is biased'towards the stationary contact 24, the contacts will close and direct current will again flow through the trembler coil.- This opening and closing of the contacts will continue and a pulsating voltage will therefore appear across the trembler coil. In order to prevent disastrous results to the permanent magnets in the magneto in case the contact 25 and 26 should be stuck closed, I provide a capacitor 30 in the connection 3| between the trembler coil and the primary winding of the magneto. This connection may also be provided with an isolating switch 32. The other side of the trembler coil is connected to the other side of the primary winding of the magneto through the connection 33. This side of the primary winding also may be grounded so as to form a return path from the spark plug. Since a pulsating voltage appears across the inductance or trembler coil a pulsating current will flow through the capacitor 30 toone side of the primary winding and through the primary winding of the magneto back to the trembler coil. It may read-" ily be seen, therefore, that the current flowing through the primary will induce an alternating current voltage in the secondary which will cause a current to flow through the distributor to a spark plug causing a spark. A spark is only desired when the magneto breaker contacts are open so that ignition, will occur at the proper time. As these contacts, when closed, are a much lower impedance path to the current than the primary winding, the pulsating current will flow through the primary winding only when the contacts are open, thus providing a spark at only the proper time. When the internal combustion engine comes up to speed theisolating switch 32 may be opened so as to disconnect the starting circuit from the primary of the magneto and the f ignition will then be. provided by the magneto.

that the condenser 30 is placed between the In the modification shown in Fig. 3 a circuit is shown similar to that illustrated in Fig. 2 except grounded side of the primary winding and-the trembler coil. This circuit may be used when grounding of the battery .is'not desired. The

starting circuit, however, will -operate similarly to that described in relation to Fig. 2.

In view of the foregoing it will be seen that I have provided a new and improved ignition arrangement for starting an internal combustion engine which makes use of the conventional magneto which provides the ignition after'the engine has been started.

Modifications of the particular arrangements which I have disclosed embodying my invention will occur to those skilled in the art, so that I do not desire my invention to be limited to the particular construction set forth and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of my invention. I

What I claim as new and desire to secure b Letters Patent of the United States is:

1. An ignition system foran internal combustion engine including a magneto having a primary and a secondary winding and an excitation means made effective by the rotation of the engine crank-shaft to induce a current in said primary winding, a breaker having electrical connection with said primary winding and being so constructed and arranged as to be periodically actuated by the rotation of the engine crankshaft so that a voltage will be induced in said means for connecting said trembler device across.

said primary winding so that ignition is provided for the engine during starting, said trembler device being short circuited by said breaker by the closing of its contacts when an ignition spark is not desired.

2. An ignition system for an internal combustion engine including a magneto having a primary and a secondary winding and an excitation means made effective by the rotation of the engine crank-shaft to induce a current in said primary winding, a breaker having electrical connection with said primary winding and being so constructed and arranged as to be periodically actuated by the rotation of the engine crankshaft so that a voltage will be induced in said secondary Winding, a source of unidirectional potential, an inductance, means for connecting said inductance across said source, means for connecting said inductance across said primary winding, and means for causing the periodic interruption of said circuit including said source and said inductance so that ignition is provided for the engine during starting, said inductance being short circuited by said breaker by the closing of its contacts when an ignition spark is not desired.

3. An ignition system for an internal combustion engine including a magneto having a primary and a secondary winding and an excitation means made effective by the rotation of the engine crank-shaft to induce a. current in said primary winding, a breaker havingelectrical connection with said primary winding and being so constructed and arranged as to be periodically actuated by the rotation of the engine crankshaft so that a voltage will be induced in said secondary winding,- and a circuit including a source of unidirectional potential and a coil, said coil having electrical connection with said primary winding through a capacitor; and means for causing the periodic interruption of said circuit so that ignition is provided for the engine during starting.

4. An ignition system for an internal combustion engine including a magneto having a primary and a secondary winding and an excitation means made effective by the rotation of the engine crank-shaft to induce a current in said primary winding, a breaker having electrical connection with said primary winding and being so constructed and arranged as to be periodically actuated by the rotation of the engine crankshaft so that a voltage will be induced in said secondary winding, and a circuit including a battery and a coil, said coil having electrical connection with said primary winding through a capacitor and an isolating switch, and means for causing the periodic interruption of said circuit so that ignition is provided for the engine during starting.

5. .An ignition system for an internal combustion engine including a magneto having a primary and a secondary winding and an excitation means made efiective by the rotation of the engine crank-shaft to induce a current in said primary winding, said primary winding having one side thereof connected to ground, a breaker having electrical connection with said primary as to be periodically actuated by the rotation of the engine crank-shaft so that a voltage will be induced in said secondary winding, and a circuit including a battery and a coil, said coil having electrical connection with said primary winding, and means for causing the periodic interruption of said circuit so that ignition is provided for the engine during starting, said grounded side being connected to said coil through a capacitor.

6. An ignition system for an internal combustion engine including a magneto having a primary and a secondary winding and an excitation means made effective by the rotation of the engine crank-shaft to induce a current in said priduring starting.

mary winding, a breaker having electrical connectlon with said primary winding and being so constructed and arranged as to be periodically actuated by the rotation of the engine crankshaft so that a voltage will be induced insaid secondary winding, and a circuit including a bat- WILLIAM H. MAYCOCK: 

